Tng caught the farthest GRB observed ever

Gamma-Ray Bursts are among the brightest explosions in the universe, and
in a few seconds they release a tremendous amount of energy, with their
light illuminating the path from the source towards us.

Although these events, as observed form Earth, are rather frequent, on April 23 at
7:55:19 UT the Swift satellite detected one of these events that
represented a scientific breakthrough: GRB 090423 (Fig. 1).

Fig.1:

As shown by follow-up observations performed with ground-based
telescopes, it was a very distant event, and soon it looked like this
was the farthest GRB ever observed. A team of international astronomers
led by Swift Italian Team and CIBO, using the AMICI prism with the Italian
Telescopio Nazionale Galileo, was able to compute its redshift at about
8.1, corresponding to a distance of more than 80 Gpc, when the universe
was only slightly more than 600 million years old (Figure 2).

Fig.2:
Isotropic-equivalent 0.3-10 keV (observed frame) luminosity light-curve
of the farthest GRB yet observed. At early times the ligthcurve is
dominated by a large flare peaking at 170 s which corresponds to just 19
seconds in the GRB rest frame.
The transition from the commonly observed shallow decay phase into the
normal
decay phase (power law decay index of 1.3) occurred as early as 4 ks obs
frame:this translates into 450 s in the GRB rest frame.

"It has been a very exciting night!" says Paolo D'Avanzo, and adds "the
detection of this unique event was possible thanks to the efforts of a well trained
team that elaborated procedures aimed to follow-up GRBs every time they
occur".

As Alberto Fernandez-Soto, a Spanish team member, puts it: "it is astonishing to
witness how rapidly the universe began forming massive stars, able to
evolve and eventually explode in such a violent way". The joint analysis
of ground-based data and high-energy data from the Swift satellite will
allow us, said Raffaella Margutti, to derive unique information about
the physical conditions in the young universe.